A variety of combustion appliances burn combustible fluids such as natural gas, propane, fuel oil and the like, in order to provide heat and/or light. Examples of combustion appliances include gas water heaters, gas clothes dryers, as stoves, ovens, gas grills, gas fireplaces, forced air furnaces, gas or oil fueled boilers for hot water heating systems, and the like. A combustion appliance may include a combustion chamber in which the fuel is burned, and the combustion gases may be vented through a flue.
In many cases, proper combustion results in a relatively low amount of undesirable gases such as carbon monoxide. However, improper combustion, which may result from a variety of potential causes, may have undesired results, such as excessive carbon monoxide production. While these combustion gases are ideally all vented out the flue, it will be recognized that in some cases this may not occur completely. Thus, it may be desirable to recognize, and recognize quickly, if and when improper combustion may be occurring, so that combustion can be corrected or, if necessary, terminated.
A need remains, therefore, for methods of recognizing and detecting combustion instability in combustion appliances.